Sear mechanism



Febz24, 1948.. W R,WEEKS f 2,436,682

SEAR MECHANI SM Filed Au s. 1946 I Inventor": Walt er RXX/je eKs His Ab'borneg Patented Feb. 24, i948 i i l Walter R. Weeks, Hamden, Conn; assignor to a w General Electric Company, a corporation of New York Application August 8, 1946, SerialNo. 689,233

r 1 My-invention relates to sear mechanism, more particularly to'sear mechanism for automatic guns, and has for its object simple and reliable means forpositively latching and securing the bolt of the gun while, at the same time, providing for therelease of the bolt with a minimum force for-the firingofthe gun.

-My invention has particular applicationto a gun in which the bolt is retained in a gun-unloaded positiorr until the gun is to be fired at which time the sear mechanism is operated to release the bolt. a It will be understood that in automatic guns, especially. machine guns of substantial size, the bolt of'thegunis thrown back upon the firing of thegun with'a tremendous force and the bolt, after striking the recoil or bufier spring, is moved forward .with atremendous force. a

In'accordance .withmy invention in one form I provide a latching arm with a latching roller on its end and with'an intermediate roller between andengaging the latching roller and a pivot pin for the arm. vThis construction provides great strength while, at the same time, giving a roller bearing action withminimum friction whenthe arm is turned to a releasing position so that the arm can be turned by a relatively small force, for example, by means of a small electromagnet.

. For a more, complete understanding of my invention reference should be had to the accompanying drawing, Fig. 1 of which is a fragmentary view partly, in section of sear mechanismiembodying my invention; Fig. 2 is a fragmentary plan view of Fig. 1; Fig. 3 is a view similar to Fig.z1'1but showing the sear mechanism in an intermediate position, while Fig. 4 is a view similar to Fig. 1 but showing the sear mechanism in the bolt-released position.

Referring to the drawing, I have shown my invention in one form as applied to the latching and securing of the gun bolt I mounted for rectilinear movement from the left toward the right, and vice versa. When the gun is fired it will be understood that the bolt l is thrown by the force of the explosion to the left hand to an extreme position into engagement with a recoil or buffer spring from which it rebounds and moves toward the right hand a short distance and is secured in the gun-unloaded position shown in Fig. 1 by the sear mechanism 2. When the gun is to. be fired the sear mechanism is operated to release the bolt, whereupon the bolt is moved by a suitable spring, not shown, in a right-hand direction to the loading position, the

4 Claims. (01. s9 1s2)' V 2 gun breech mechanism is locked in place and the gun fired.

In accordance with my invention the sear mechanism 2 comprises a pivoted arm or frame consisting of two parallel plate members 3 and 4 secured rigidly together by a laterally extending: pin- 5 extending between their right-hand ends. This arm or frame, constituted by the members 3, 4 and 5, is mounted pivotally on a stationarytpivot pin 6 constituting a stationary roller having its ends secured in trough-shaped supporting member I forming part of the gun, spaced collars 8 and 9 being provided on opposite sides of thelframe."

For the purpose of securing the bolt I, a latching roller lllislmounted on the left-hand end of the frame between the members 3 and 4 which roller, as shown in Fig. 1, engages a projection I l on the bolt I thereby to secure the bolt in its gun-unloaded-position. The roller I0 is provided withaa relatively small trunnion l2 at each end, which trunnions constituting journals extend through parallel slots I3 in the members 3 and 4, the slots extending parallel with the plane surface of the projection II and substantially at right angles with the arm. Also mounted on the members 3 and 4 is a second roller l4 provided with a trunnion I5 at each end, these trunnions extending through bearing apertures in the members '3 and 4. This roller I4 is positioned directly between the pivot pin 6 and the roller It] so as to engage the pin and the roller l0.

- When the roller lllis in its holding position shown in Fig. 1 with its trunnions bearing againstv the lower end walls of theslots I3 its axis of rotation lies in a plane passing through the axis of rotation of the roller- [4 andthe center of the pin 6. The, members. 3 and 4 are additionally secured together at their left-hand ends by a cross member I6 which forms a seat for the upper end of a biasing spring 11, the lower end of which bears against the support I. By means of the spring 11 the'frame and roller l0 are biased in a clockwise direction about the pin 6 to the holding position shown in Fig. 1 in which position the right-hand end l8 of the frame engages the supporting member I.

When the bolt l' is to be released an operating link 19 is moved toward the left hand, as by an electromagnet, thereby to move the frame and roller l4 counterclockwise about the pivot pin 6, the frame being provided with a cross pin 20 having one end 2| projecting into a slot 22 in the link [9. During the counterclockwise releasing movement of the frame the roller l4 rolls tions shown in Fig. 3. Thereafter, as the frame:-.

and roller H] are turned to their fullyboltere leasing positions shown in Fig. 4 the roller luis" caused to slide somewhat, as: welli-asiroll onntha surface of the projection J5,

The rolling action provides for the minimum friction and consequently minimum requiredrope erating force applied to the link I9 during the first part of the releasing movement to =tlie1position shown in Fig. 3 and, after the movement of the pa-rts.has;thus.-beerr started,-and=thein;-inertias. overcome, the subsequent slidin action; between the-'roll'er I-ll'on-the projection; Ill: doesi;not-require zany appreciable:additionaliiiorcerapplieckto the; link" L95, Moreover;,;whem t'heelinkt, l'fizisi-op erated: by an;electroma'gneiathe force appliedzto the link 1 by theiarmatuna ofi1 thezmagnet i will; be increaseds as, the; armature of magnet; ape proachesits=iul1yattraotedipositinn.

It, will. be: observedxthat thissconstnuctinmprm vides; great strengthxbecauseithe fiorcezwithi which: the projection; H engagesitlie'mllen H) asthezholiz lvi'sithrown toward.themightihandinomztherhufien spring is transmitted from tha roiiemlfl 'itozthe roller. M .andiirom the roller: meta the relatively large; and; rigid pin 6:". Theaengaging suriacesof theprojection 9011112113 boiiflsisfli-diwhd anginlarlyt that? a; perpendiculan-lime passing througlr its point: of engagement: wtthi theirulleri 120;. as shown in Figs 1;.extendsaneaaz on throughithe eerie ter. line of the pimft soithatmhezcomponentioiiithe force of: the bolt tendin' itottumsthe fram is very sm'a'lii and. any tendency 'to tiirmthe :trame in: a counterclockwise: direction is overcome: by the biasing spring IJ. This:biasingv spring Eh is strong enougli to: assure-that itireturns: the fi ame: and parts carriGd'Dm-ii'; t'o:the:latching positiomoi Fig intime tooatch -thebolfil omiifswebound from the bufier spring I While I' have-showrp a pamtisular embodiment of my: invention; it wilpbeunderstood; oficoursez that I do not Wiht0b8.'-limited?UhGTBCG-SiHBU manymo'dificationsimay bei-made-andrli therefore contemplate by theappendediciaimsiltoicovern any such: modifications as fall-= within the trues-spirit" and: scopeoi'my'inventions What: IJcIaimas: new and desire tmsecure -By Letters'Patentof the 'Unitedfitates isz 1. Sear mechanism comprising an arm, a pivot pin for said arm constituting a roller, a first latching roller on said arm, a, second roller on said arm between and engaging said pivot pin and said first roller, means for moving said arm about said pivot pin to a predetermined latching position, and means for turning said arm about saidtpivotpim to -move saiiiifirst'rollento a releasingpositiomwhereby firstzroller rolls on said second roller and said second roller rolls on said pivot pin.

2. Sear mechanism for securing the bolt of a gun comprising an arm, a stationary pivot pin for saidrarm constituting a stationary roller, a first-tlatchingtrollerr-on said arm, a second roller on said arm: between and engaging said pivot pin and saidfirstrzoller, a spring biasing said arm about said pivot" pin to a latching position, and meansio'r turning said arm about said pivot pin against the force of said spring to move said first roller to: atreleasing;l zosition:v whereby said-- first rolle -rolls omsaid isecond; roller; and said. second hollerrolls'onisaidipivot-pin.

3-. Sea-r;- mechanism comprising; aiz-ame, a. stata tionarg: pivot pin; for; said; frame constituting, a

stationary,- nollen, saidqfra-meq being provided, with oppositely disposed paralleLs-lotsimone end-sub,- stantially at might; angles with; said-:fname. a first latching; roller ,on-v saidy frame; provided: with: journa-lsiextending into said: slots,, axsecondroller between; andyengagingssaidinivot; pin: and: said. first roller, and means for turning saidcfirameaboutr. said-.- pi-votmirr, toimove said: firstroller to areleasing; posiifionvwherebyr said firstlroller rollson said;;secnnd;;r.oller; saidl seconi'roller; rolls; on said pivot pin anditheziournalsrofisaid firstiroller'move inssaid slots:.

4; Sear mechanismzfor; securing: thelbflltiofl a; gnnigcomprising; a. frame; a: stationary pivot. pin said.- frame constituting; a; stationary roller; said: 'firameebeing; provided. with oppositedly: disiposed: parallelq slots: in one end; substantially" at right ang-lestwith said frame, a; latching; roller OII'lSfiid} frame, provided:.withitrunnionsiextending into: said-sslotss a; seoondzroller between and; en. gaging-said piVOiBPiII-fiMIdSHIid firstaroller; a stoli tomsaid armgzaispringibiasing; saidiarm aboutsaid'. pivot. pinaagainst: saidzstopvta ailat'ching' position;

and means for turning said frame aboutsaid-pim against thesforce ofz'saidpspringrtormoveisaidfirst roller: tonal;releasing:v positiom whereby said-first mllen rolls; said; second: roller; said. second roller; DQHSEOHLSHfidi pivot: pinianmmg trunni n sl f saidfirst'rollen meve ixzsaidtslotsz.

WALTER. a; WEEKs; 

